1. Field of the Invention
The present invention pertains to resource management and memory management algorithms for use with electronic printing and electronic reprographic systems. The resource management algorithms are for optimally managing and allocating page memory and disk storage of a printer. Three scheduling algorithms are used: an offset algorithm, for allowing a small period of time (pitches) between image request time and print time; an advanced scheduling algorithm, for scheduling a disk as necessary to retrieve the images in a print set prior to printing by scheduling a certain number of pages ahead; a consecutive set scheduling algorithm, which is a modification of the advanced scheduling algorithm in which memory usage and disk are scheduled for consecutive sets to reduce the number of skips between sets. The invention further pertains to a group of memory managements swapping algorithms from which can be selected an optimum strategy dependent upon the particular resources of memory and disk bandwidth available for reducing pitch skips and improving turn around time.
2. Discussion of the Background and Related Art
Data management systems and techniques for improving throughput in such systems are disclosed in U.S. Pat. No. 4,241,420 to Fish et al. and in U.S. Pat. No. 4,339,503 to Hawley. Fish et al. disclose a controller for supervising the transfer of data between a disk memory and RAM memory in order to avoid delays in transfer. The Hawley patent discloses a controller for controlling the transfer of data between a disk memory and a high-speed limited capacity RAM memory.
Further, the prior art discloses a number of references relating to memory management systems for electronic printers. U.S. Pat. No. 4,910,611 to Cok discloses a method for interactive image processing wherein various operations are carried out upon images. In order to increase efficiency, each command is analyzed to determine which parts of the image will be required to complete the command. In addition, memory transfers between main memory and an auxiliary disk memory are avoided by using memory swapping. U.S. Pat. No. 4,445,195 to Yamamoto discloses a recording system of variable length picture information wherein a picture image is scanned into a device and stored on a disk. The picture can then be retrieved from memory so that it can be printed. The length of a particular picture element is stored along with the actual data so that it is easier to determine the length of the picture. U.S. Pat. No. 4,511,928 to Colomb discloses a system and method for high quality image reproduction wherein an image can be scanned and stored. Two processors are provided for controlling all of the operations of the copier including the print-while-store function.
U.S. Pat. No. 4,894,646 to Ryman discloses an image processing system and method for manipulating images in an image processing system where each image in the system is subdivided into a plurality of sub-images which are processed independently of one another. The Ryman patent relates to the efficient processing of large digital images where the image storing requirements exceed the capacity of the memory of the processor on which the image data is being processed or in which the addressing capability of the processor is inadequate to handle the image data or both. The images stored in the system are maintained in a secondary store and only portion of the image are available for manipulation at any one time in a primary store. The manipulation of some images is determined by a modified Least Recently Used algorithm which minimizes data swaps between the primary and secondary stores.